We adopt the atomic norm as the sparsity-inducing norm for \(\mathbf {h}\) .
The atomic norm of \(\mathbf {h}\)  over the dictionary \(\mathcal {A}\)  is defined as [1]}
\(\Vert \mathbf {h} \Vert _\mathcal {A} = \inf \left\lbrace  \sum _l |\alpha _l| \bigg | \mathbf {h} = \sum _l \alpha _l \mathbf {a}_l, \mathbf {a}_l \in \mathcal {A} \right\rbrace ,\) 
